Merge changes I1360deb0,Id9a9eb85,I7f05f2ee,Ie48da88d into qt-dev

* changes:
  Fix issues with animations when the stack is expanded.
  Prevent a crash when touching the stack while it's flinging out of the dismiss area.
  Remove the max rendered children code.
  Stability and logic fixes to PhysicsAnimationLayout to address bugs that leave Bubbles in a bad state.